Which two are true regarding external tables？ （） A: AExternal tables can be updated. B: BExternal tables are read-only tables. C: CIndexes can be created on external tables. D: DIndexes cannot be created on external tables.
Which two are true regarding external tables？ （） A: AExternal tables can be updated. B: BExternal tables are read-only tables. C: CIndexes can be created on external tables. D: DIndexes cannot be created on external tables.
如果希望横向合并后的数据文件只包括第一个数据文件中的个案，则应当选择（） A: ABoth file iprovide cases B: BExternal file is keyed table C: CWorking data file is keyed table D: DIndicate case source as variable
如果希望横向合并后的数据文件只包括第一个数据文件中的个案，则应当选择（） A: ABoth file iprovide cases B: BExternal file is keyed table C: CWorking data file is keyed table D: DIndicate case source as variable
1